In general, a cartridge or blade unit of a safety razor has at least one blade with a cutting edge which is moved across the surface of the skin being shaved by means of a handle to which the cartridge is attached. Some shaving razors are provided with a spring biased cartridge that pivots relative to the handle to follow the contours of the skin during shaving. The cartridge can be mounted detachably on the handle to enable the cartridge to be replaced by a fresh cartridge when the blade sharpness has diminished to an unsatisfactory level, or it can be attached permanently to the handle with the intention that the entire razor be discarded when the blade or blades have become dulled. Razor cartridges usually include a guard which contacts the skin in front of the blade(s) and a cap for contacting the skin behind the blade(s) during shaving. The cap and guard can aid in establishing the so-called “shaving geometry,”, i.e., the parameters which determine the blade orientation and position relative to the skin during shaving, which in turn have a strong influence on the shaving performance and efficacy of the razor. The cap can comprise a water leachable shaving aid to reduce drag and improve comfort. The guard can be generally rigid, for example formed integrally with a frame or platform structure which provides a support for the blades. Guards can also comprise softer elastomeric materials to improve skin stretching.
Shaving systems often consist of a handle and a replaceable cartridge in which one or more blades are mounted in a plastic housing. After the blades in a cartridge have become dull from use, the cartridge is discarded, and replaced on the handle with a new cartridge. These types of shaving systems that utilize a variety of connection schemes to affix the cartridge to the handle have become popular. The connection scheme allows the consumer to easily, repeatedly, efficiently and intuitively load and remove the new and used cartridges from the handle and provides the necessary retention forces to maintain the integrity of the handle-to-cartridge attachment during shaving.
The connection scheme must be robust enough to provide the necessary retention forces to maintain the integrity of the handle-to-cartridge attachment during shaving. The attachment of a razor cartridge to razor handle can provide sufficient retaining force to secure the razor cartridge to the razor handle over a wide variety of shaving conditions. Some shavers use very high forces when shaving and some razors have a hair trimming system mounted on the side or back of the razor cartridge. In contrast, razors that use razor cartridges that are releasably connected can provide low attachment and release forces to facilitate easy changing of cartridges by a shaver.
The razor cartridge of many razors can also be in pivotal relationship with the razor handle. Most existing razors typically provide the mechanism that enables this pivot relationship on the razor cartridge or at the interface of the razor cartridge and razor handle. These pivot mechanisms can be expensive to manufacture and can represent a significant fraction of the total manufactured cost of a razor cartridge. Accordingly, there is a need for a simpler, less expensive, more intuitive and reliable shaving handle-to-cartridge connection.